Demo: http://projects.bryanmcbride.com/login/login.html
Download: http://projects.bryanmcbride.com/login/sqlite_php_login.zip

The basic ODK workflow:

• Design a data collection form
  • ODK forms follow the XForms XML standard and can be built using ODK’s web-based build application. There are several other tools available for building these forms, and they can also be built manually with a simple text editor.

• Install the ODK Collect app on your Android smartphone
  • This is a generic mobile data collection app that transfers data between your phone and your database server.

• Configure the ODK Aggregate server to manage your collected data
  • This is a Java based application, which can be deployed on Google’s App Engine infrastructure, or configured locally to connect with a MySQL or PostgreSQL database.

GIS Potential:

ODK has the potential to fill a crucial gap that has existed for years between low-end recreational GPS units (think eTrex) and high-end GPS data collectors (think Trimble). Recreational GPS units are dirt cheap and fairly accurate these days, but they lack any sort of sophisticated data collection capabilities. You get waypoint name and description fields, and a selectable symbol if you are lucky, but this just won’t cut it for most GIS projects where data integrity is paramount. Most recreational GPS units are built on closed platforms (Garmin, Magellen) while the industry standard for high end units seems to be  Windows Mobile (ArcPad, TerraSync).

Smartphones however, offer reasonably cheap hardware paired with sophisticated open operating systems. Most have decent cameras and GPS sensors and they are connected to the web by default. There are tons of GPS and mapping apps already out there, but what we really need is a generic application that works with our custom data dictionaries or forms- and this is where ODK shines!

Tips, Tricks, and Hacks:

As a Google project, ODK works seamlessly with App Engine and Fusion Tables, which is cool in and of itself, but hardcore GIS requires more tweaking. A Java application that uses PostgreSQL just screams out for PostGIS and GeoServer integration! Here’s what you need to know to get this system up and running…

Prerequisites:

• Android smartphone (for ODK Collect)
• Java servlet containter (for ODK Aggregate)- tested on Jetty and Apache Tomcat 6
• GeoServer 2.1.0 or higher for SQL Views (can use database views with < 2.1.0)

Lessons Learned:

• Play around with the App Engine install first to see what you can do with ODK before you dive into configuring locally
• Download the configuration wizard from the Google code repository: http://code.google.com/p/opendatakit/downloads/list
• ODK Aggregate can run in the Jetty servlet container that ships with the GeoServer windows service installer, but I would recommend deploying on Tomcat…
• Make sure you create your intended ODK postgres database using the PostGIS template!
• Setup your ODK database as a GeoServer data store and make your layers as GeoServer SQL Views
• Use the following bit of PostGIS magic in your SQL View to transform the lat, lng coordinates in the ODK database into GeoServer friendly WKB geometries: ST_GeometryFromText(‘POINT(‘||”FORM_FIELDNAME_LNG”||’ ‘||”FORM_FIELDNAME_LAT”||’)', 4326) AS “the_geom”
• You will have to manually enter the layer bounding box values as you probably won’t have the full extent of your data populated in your table yet. To be safe, you can enter: -180, -85.051, 180, 85.051, which covers the globe avoiding the poles.

ODK + PostGIS + GeoServer + Leaflet:

An exercise in open source mobile GIS data collection: http://geoserving.net/odk_geoserver

Forgetting about silly things like SDE and the “Data Interoperability Extension”, one is left with few options. No direct editing of PostGIS, no WFS-T support… One is left desperately waiting in anticipation for zigGIS 3.0.  A simple workaround to avoid having to perform multiple ETL processes or FTP’ing shapefiles from desktop to server is to use Dropbox.

• Install dropbox on your GeoServer box
• Set up a shapefile directory data store on your dropbox folder
• Share this folder with your fellow collaborators
• They load the shapefiles from the shared directory on their local machine and edits are automatically pushed to the GeoServer box and updated in your output data streams

Nothing to it! Use this information cautiously, and remember that concurrent editing against shapefiles can potentially get you into trouble…

The OpenLayers Mobile code sprint in Lausanne appears to have been a huge success. The new Mobile Demos speak to the great progress that was made over a single week.

While I was in Florida on vacation last week, I received an email from the NYS GIS listserv that the (ancient) New York State Digital Orthoimagery Application was (finally) being replaced with a (functioning) application called New York State Orthos Online. I was happy to see that the state didn’t fall for the old ESRI flex viewer template, but actually came up with a nice application built on the ArcGIS JavaScript API. We can finally browse and download imagery without having to open Internet Explorer!

I decided to take the fruits of all this labor and build a new mobile web application that may or may not be useful to others out there. The result is the NYS Orthos Online Mobile application (NYSOOM). NYSOOM is basically a touch-optimized mobile version of the NYS Orthos Online site. I took the ArcGIS REST services hosted by the state and plugged them into the OpenLayers jQuery Mobile example that was a product of the code sprint in Lausanne. So if you are curious about the Empire State, break out your smartphone and peruse through the entire imagery collection (1994-Present). The current URL of the application is http://geoserving.net/nysoom, but if there is any interest I may move it to another domain.

Let me know what you think!

PS- You can check out the application on your desktop using Google’s Chrome browser.

This has been a fun little project and a departure from the norm- as there is no GeoServer backend powering this application. All of the vector data is stored in a PostGIS database and fetched as needed via a few custom PHP scripts. Data is exchanged in GeoJSON format and the larger datasets (parcels, buildings) are limited by the user viewport extent.

This method works great for a municipality with a relatively small geographic footprint and dramatically simplifies the system architecture.

They key to this approach is to take advantage of the PostGIS output functions (ST_AsGML, ST_AsGeoJSON, ST_AsKML).  If you are working with large datasets, you’ll want to limit the amount of data you throw at the browser by registering a ‘moovend’ event, grabbing the viewport coordinates, and returning only the features that fall within the current map extent.  For something like tax parcels, you will have to set tight scale thresholds so the user is forced to query at a reasonable extent.  You’ll know if you screwed something up when you try to force someone running IE6 to load a 50MB KML file in their browser and it blows up in their face!

I’ve put together some quick and dirty documentation  on setting up an Apache + PHP + PostGIS development environment using the excellent BitNami WAPPStack package for Windows.  The documentation covers:

• Downloading and installing the BitNami WAPPStack
• Configuring Apache and PostgreSQL to run as services
• Installing PostGIS in the WAPPStack package
• Configuring PostgreSQL and phpPgAdmin to allow access from outside IP addresses

WAPPStack & PostGIS 5 Minute Install Documentation

If you’ve ever had the pleasure of playing around with PostGIS before, you’ll know why I’m so excited about this. If not, I highly suggest you head over to OpenGeo’s Intro to PostGIS workshop. Simply put, PostGIS integrates all the spatial functions and processing tools you could ever ask for within a (free) relational database. This means that you can run spatial queries and geoprocessing tasks directly against your data store without having to mess with any bloated middleware (think Arc…). PostGIS is the go-to data store for all the popular open source GIS packages and even plays well with ArcGIS! Best of all, the spatial functions are exposed as SQL queries- this means you can build powerful GIS web applications on top of PostGIS with a scripting language such as PHP.

Image courtesy of OpenGeo (http://workshops.opengeo.org/postgis-intro/introduction.html)

You can have multiple popups open at once, unpin them from their feature and expand to fit the screen. Check it out!

• Set “resize” transition effect on all single tile WMS layers
• Added a nice little animated loading gif for all you impatient clickers out there
• Included a KML upload utility (currently does not support compressed KMZ format)
• Included a Spot Elevation tool, which utilizes the USGS Elevation Query Web Service
• Upgraded to ExtJS 3.2.1
• Upgraded to Development Version of OpenLayers 3 (includes upgrade to GmapV3)
• Added 2010 Tax Parcels layer

Enjoy the updates and keep in touch!

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